416 EXPERIMENT STATION RECORD. 



cially as related to critical periods of crop growth. A close relation was found 

 to exist between the yield and the weather, the yield depending largely upon the 

 adaptation or adjustment of the crop to the weather conditions. 



The results indicate the great importance of adaptation of season and crop, 

 with reference especially to rainfall, late frost, selection of varieties and seed, 

 rate and time of seeding, use of fertilizers, etc. It is shown that by discrimi- 

 nation in the selection of seed, rate and time of seeding, and use of fertilizers, 

 unfavorable weather conditions can be to a considerable extent overcome or 

 controlled. For example, fertilized crops give better yields in a dry season 

 than unfertilized. 



Practical ventilation, C. F, Bennett (Abs. in Lit. Digest, 50 (1915), No. 11, 

 pp. o.'f.'f, 5.'i5). — The author in this article condemns the usual "plenum " system 

 of ventilation which seeks to flush out the impurities by introducing large 

 quantities of outside air. He maintains that the better procedure is to keep 

 the pressure in a room slightly below that of the atmosphere instead of above 

 it as in the plenum system, and tlien remove the relatively small quantity of 

 impure air, admitting just enough outside air to replace this. 



The measurement of humidity in air, Tschaplowitz [Ztschr. Hyg. u. 

 Infektiomkrank., SO (1915), No. 2, pp. 193-218, figs. 2).— Tests with a number 

 of psychrometers of different styles are reported, and information is given 

 regarding the use* of these instruments in recording the humidity of dwelling 

 houses, schoolrooms, etc. 



Protection of life and property against lightning, O. S. Peters (Jour. 

 Wash. Acad. Sci., 5 (1915), No. 19, pp. 625-628). — Tliis is an abstract of a paper 

 reporting a survey of statistical data relating to life and property hazards from 

 lightning and describing existing methods of protection against lightning. 



It is stated that " the property loss by lightning for tlie entire United States 

 is approximately $8,000,000 per year, of which by far the greater part occurs in 

 rural districts." Approximately 500 persons are killed and 1.000 injured by 

 lightning annually in the United States, about 90 per cent of the casualties 

 occurring in rural districts. 



Taking lightning rods as thoy come in the general run of installations, they 

 reduce the fire hazard from liglitning from SO to 90 per cent in the case of 

 houses and as much as 99 per cent in the case of barns. Of tlie ordinary metals 

 available for lightning rods, one Is about as good as another. Resistance to 

 atmospheric and soil corrosion is the chief essential to be considered. Good 

 mechanical construction is a prime essential to permanency, and the resistance 

 of the earth connection should he made as low as practicable, not exceeding 15 

 or 20 ohms at any time. Aerial terminals with points should be placed at all 

 chimneys, gables, and other projections. Conductors should be so installed as 

 to furnish two or more widely separatetl paths to the earth. 



The property loss from lightning is not considered suflicient to make universal 

 protection against it a paying investsient. It is justitiod as an investment only 

 when risk to human life is involved or the property risk is great enough to make 

 protection more economical than insurance. A high degree of safety is afforded 

 by a well-rodded building, the next degree of safety is in an unprotected house, 

 and the least in the open or in unprotected outbuildings. 



Efficacy of lightning rods, J. W. Smith (Ohio Nat., 15 (1915), No. 4- PP- 

 Ji37--i-'i2). — This article briefly summarizes the results of a study of the damage 

 caused by lightning and the efficiency of lightning rods as a protection against 

 lightning, particularly in the north-central States. 



It is shown that in this region the damage from this source is considerable. 

 The loss and damage are far greater (75 per cent) in the country than in the 



